The present invention relates to the field of perfumery. More particularly, it concerns new esters capable of liberating an odoriferous alcohol and comprising, in proximity, a carbamoyl function facilitating the liberation of the said odoriferous alcohol.
The perfumery industry has a particular interest in compounds which are capable of prolonging an odoriferous effect over a certain period of time, in particular in order to overcome the problems encountered when using perfuming ingredients which are too volatile. U.S. Pat. No. 5,649,979 in particular discloses compounds which, under certain activation conditions such as light, heat or the presence of enzymes, in particular lipases, are capable of liberating an odoriferous molecule over an extended period of time. These compounds can have various applications. The washing of textiles is a particular field in which there is a constant quest to enable the effect of perfuming substances to be experienced for a certain period after washing and drying. Many substances having fragrances which are particularly suitable for this type of application are, in fact, known to lack tenacity on laundry, or do not remain on the laundry when rinsed, with the result that their perfuming effect is experienced only briefly and not very intensely. Given the importance of this type of application in the perfuming industry, research in this field has been sustained, in particular with the aim of finding new, even more effective solutions to the aforementioned problems.
Surprisingly, we have discovered the existence of new esters comprising a non-substituted or mono-substituted carbamoyl function capable of liberating, in a controlled and effective manner, an odoriferous alcohol without the aid of an activator as described in the prior art. Furthermore, these compounds have, quite unexpectedly, excellent staying-power or tenacity, especially on laundry, making them very suitable precursors in particular for applications associated with functional perfumery. Odoriferous molecules present as such in products such as washing powders or detergents generally have little staying-power and are consequently often eliminated in the rinsing water during machine washing, for example. Conversely, the compounds according to the invention, owing to their substantivity and the controlled liberation of the odoriferous alcohol, can impart a fragrance and a freshness to laundry which will last beyond the rinsing and drying processes.
The compounds of the present invention have the following formula: 
in which the dotted line indicates the location of a single or double bond; R1 represents a radical derived from an odoriferous alcohol of the formula R1OH; R2 represents a hydrogen atom, a linear or branched, saturated or unsaturated C1-C30 hydrocarbon radical, or an aliphatic or aromatic cyclic compound having 5 or 6 carbon atoms, this radical R2 possibly comprising heteroatoms of oxygen, sulphur or nitrogen, in particular quaternary ammonium functions; the symbols R3, R4 and R4xe2x80x2, considered independently, represent a hydrogen atom, a linear or branched, saturated or unsaturated, if necessary substituted, C1 to C20 hydrocarbon radical possibly comprising one or more heteroatoms, or, when considered together with the carbon atoms to which they are bonded, can form aromatic or aliphatic monocyclic, bicyclic or tricyclic compounds, the radicals R3, R4 and R4xe2x80x2 possibly comprising functional groups of the ester and carbamoyl type so as to liberate several molecules of odoriferous alcohol R1OH per single molecule of precursor. This is the case in particular for the products of pyromellitic anhydride, as indicated hereinbelow.
These compounds are capable of liberating an odoriferous alcohol of the formula R1OH during the hydrolysis of the ester bond. Odoriferous alcohol is taken here to mean an alcohol commonly used in perfumery, that is to say suitable as a perfuming ingredient for the preparation of perfumes or perfumed articles. Although it is not possible to provide an exhaustive list of the currently known alcohols of the formula R1OH usable according to the invention, the following can be named as examples: anisyc alcohol, cinnamic alcohol, fenchyl alcohol, 9-decen-1-ol, phenethylol, citronellol (3,7-dimethyl-6-octen-1-ol), 3-methyl-5-phenyl-1-pentanol (origin: Firmenich SA, Geneva, Switzerland), Mayol(copyright) (7-p-menthan-1-ol; origin: Firmenich SA, Geneva, Switzerland), dihydromyrcenol (2,6-dimethyl-oct-7-en-2-ol), alpha-ionol, tetrahydro-ionol, geraniol, nerol, (Z)-3-hexen-1-ol, 1-hexanol, 2-hexanol, 3,3,5-trimethyl-hexanol, 3,4,5,6,6-pentamethyl-heptan-2-ol, 5-ethyl-2-nonanol, cis-6-nonenol, 6,8-dimethyl-2-nonanol, 2,6-nonadien-1-ol, borneol, 1-octen-3-ol, 4-cyclohexyl-2-methyl-2-butanol (origin: Firmenich SA, Geneva, Switzerland), 6-ethyl-3-methyl-5-octen-1-ol, 3,7-dimethyl-oct-3,6-dienol, 7-methoxy-3,7-dimethyl-octan-2-ol, methyl-4-phenyl-2-butanol, 2-methyl-1-phenyl-2-propanol, 1-phenylethanol, 2-phenylethanol, 2-phenylpropanol, 3-phenylpropanol, 2-methyl-5-phenylpentanol, 2-methyl-4-phenylpentanol, 3-methyl-5-phenylpentanol, cyclomethylcitronellol, decanol, dihydroeugenol, 8-p-menthanol, 3,7-dimethyl-1-octanol, 2,6-dimethyl-2-heptanol, dodecanol, octanol, undecanol, 4-methyl-3-decen-1-ol, eucalyptol, eugenol, Florol(copyright) (tetrahydro-2-isobutyl-4-methyl-4(2H)-pyranol; origin: Firmenich SA, Geneva, Switzerland), 2-phenoxy-ethanol, isoeugenol, linalol, Tarragol(copyright) (2-methoxy-4-propyl-1-cyclohexanol; origin: Firmenich SA, Geneva, Switzerland), vanillin, ethyl-vanillin, anethole, farnesol, cedrenol, menthol, p-menth-8-en-3-ol, 3,3,5-trimethyl-cyclohexanol, 2,4,6-trimethyl-3-cyclohexenyl-methanol, 4-(1-methylethyl) cyclohexyl-methanol, terpineol, tetrahydromuguol, 3,7-dimethyl-3-octanol, Polysantol(copyright) [(E)-3,3-dimethyl-5-(2xe2x80x2,2xe2x80x2,3xe2x80x2-trimethyl-3xe2x80x2-cyclopenten-1-yl)-4-penten-2-ol; origin: Firmenich SA, Geneva, Switzerland], 2,2,6-trimethyl-alpha-propyl-cyclohexane propanol, 5-(2,2,3-trimethyl-3-cyclopentyl)-3-methylpentan-2-ol, 3-methyl-5-(2,2,3-trimethylcyclopentyl-3-enyl)pent-4-en-2-ol, 2-ethyl-4(2,2,3-trimethylcyclo-pentyl-3-enyl)but-2-en-1-ol, 4-(5,5,6-trimethylbicyclo[2.2.1]hept-2-yl)-cyclohexanol, 2-(2-methyl-propyl)-4-hydroxy-4-methyl-tetrahydropyran, 2-cyclohexyl-propanol, 2-(1,1-dimethylethyl)-4-methyl-cyclohexanol, 1-(2-tert-butyl-cyclo-hexyloxy)-2-butanol, 1-(4-isopropyl-cyclohexyl)-ethanol and 1-(2,2,3,6-tetramethyl-cyclohex-1-yl)-3-hexanol (origin: Firmenich SA, Geneva, Switzerland).
The special feature of the invention resides in the fact that hydrolysis, which causes liberation of the alcohol, is assisted by the nucleophilic group adjacent to the ester function, the CONHxe2x80x94R2 group. This assistance has a completely unexpected advantage, i.e. it permits the cleavage of the ester bond by hydrolysis in simple alkaline conditions, as shown by the following scheme: 
Such conditions are the normal conditions for washing textiles, for example, during the course of which a change in pH takes place. The pH changes from a value corresponding to an acid environment to values corresponding to a neutral or even basic environment during the course of the washing cycle, thus allowing the compounds according to the invention to hydrolyse.
Furthermore, the reaction is catalysed naturally in the presence of heat. This is the case e.g. when laundry is dried, in particular in an electric dryer, or ironed, especially steam ironed. The hydrolysis reaction leads to the formation of an odoriferous molecule R1OH, in which R1, has the meaning indicated hereinabove, and a residue of the initial precursor, an imide, this residue generally being odourless.
The reaction does not require any other external agent such as the presence of a lipase, as described in the prior art.
The compounds according to the invention have thus proved to be advantageous precursors of odoriferous alcohols. The hydrolysis reaction of the ester bond in the most simple conditions, as mentioned hereinabove, can also be controlled from the kinetic point of view through the choice of the substituent R2: the release of the odoriferous alcohol will be carried out more or less rapidly as a function of the chain length or the degree of branching of the chain. This enables the system according to the invention to be adapted to the requirements of a particular application and therefore represents an indisputable advantage.
The invention also relates to a process for intensifying or prolonging the diffusion effect of the characteristic fragrance of an odoriferous alcohol in textiles, characterised in that these textiles are washed in the presence of a detergent and, optionally, subsequently treated with a fabric softener, the said detergent and/or softener comprising a compound according to the invention.
Of the compounds of the formula (I) according to the invention, the most highly rated are the 2-carbamoylbenzoates of the formula: 
in which the symbols R5, R6, R7 and R8, taken independently, each represent a hydrogen atom or a linear or branched C1 to C20 alkyl group and, when taken in pairs, can form one or more cyclic compounds.
Preferred examples are 2-(octylcarbamoyl)benzoate of 3,7-dimethyl-6-octenyl, 2-(dodecylcarbamoyl)benzoate of 3,7-dimethyl-2,6-octadienyl and 2-(dodecyl-carbamoyl)benzoate of 3,7-dimethyl-6-octenyl.
In addition, of the compounds of the formula (I) according to the invention, the 3-carbamoylpropanoates and the 4-carbamoylbutanoates are also highly rated and have the following formulae respectively: 
in which the symbols R3, R4, R5, R6 and R7 each represent a hydrogen atom or a linear or branched C1 to C20 alkyl radical possibly containing one or more heteroatoms.
Especially preferred examples are 3-(octylcarbamoyl)propanoate of 3-phenyl-2-propenyl, 4-(octylcarbamoyl)butanoate of 3,7-dimethyl-2,6-octadienyl and 3-(octylcarbamoyl)propanoate of 3,7-dimethyl-2,6-octadienyl.
Furthermore, the compounds having a double ester-carbamoyl functional group can prove advantageous since they are capable of liberating two molecules of odoriferous alcohol per single molecule of precursor. Preferably, these compounds will have the following formulae: 
in which R1 and R2 are as defined for formula (I). Preferred examples of the compounds (Id) are 2,5-di(octylcarbamoyl)terephthalate of di(3,7-dimethyl-2,6-octadienyl), 1,3-di(octylcarbamoyl)isophthalate of di(3,7-dimethyl-2,6-octadienyl) or a mixture of these two compounds.
The compounds according to the invention can be prepared from commercially available compounds by conventional methods. Generally speaking, starting from commercial starting materials (acids or anhydrides), an ester bond is formed by conventional esterification of the carboxyls or by acid catalysis. Then, the remaining carboxylic acid function is coupled to a primary amine, respectively to ammonia, to give the monosubstituted, respectively non-substituted, carbamoyl function.
For example, the 2-carbamoylbenzoates (Ia) are prepared from phthalic anhydride (or its derivatives) in accordance with the following scheme: 
The compounds of the formula (Ib) and (Ic) can be synthesised from succinic or glutaric anhydrides, as shown in the following scheme: 
Finally, the bifunctional compounds of the type (Id) are prepared from pyromellitic anhydride according to the same principle, as shown in scheme 3.
All the symbols used in the above schemes are as defined for formula (I).
The compounds according to the invention can lend themselves to any application requiring the effect of rapid or prolonged liberation of an odoriferous component as defined hereinabove. They can be used in particular in functional perfumery, particularly applications such as liquid or solid detergents for the treatment of textiles and fabric softeners, in which the fragrance of the ingredients must be effectively imparted to the textile during washing. One of the chief advantages of the invention resides in the fact that the compounds impart an intense fragrance to the laundry, produced by an odoriferous alcohol, which would not be detected on the laundry over a sufficiently long period if the alcohol had been used as it is, i.e. without a precursor.
The compounds according to the invention can be used as perfuming ingredients for laundry in all types of detergent or softening bases in which these compounds are stable. Preferably, and as is generally the case, detergents with a basic pH will be used. In this case, the compounds will have to be protected from premature hydrolysis, for example by encapsulation. With respect to the fabric softeners, products with a pH less than 7 are preferred. For example, detergents of the type described in WO 97/34986 can be used. Furthermore, softening bases such as those described in U.S. Pat. Nos. 4,137,180 and 5,236,615 or EP 799 885 can be selected. Other typical detergent and softening compositions which can be used are described in works such as Ullman""s Encyclopedia of Industrial Chemistry, vol. A8, pages 315-448 (1987) and vol. A25, pages 747-817 (1994); Flick, Advanced Cleaning Product Formulations, Noye Publication, Park Ridge, N.J. (1989); Showell, in Surfactant Science Series, vol. 71: Powdered Detergents, Marcel Dekker, New York (1988); Proceedings of the World Conference on Detergents (4th, 1998, Montreux, Switzerland), AOCS print.
Naturally, however, the use of the compounds according to the invention is not limited to the products mentioned hereinabove. These compounds lend themselves equally well to all the other uses common in perfumery, namely the perfuming of soaps and shower or bath gels, hygiene products or hair care products such as shampoos, as well as deodorants and air fresheners and also cosmetic preparations.
The compounds can also be used in applications such as detergent compositions or cleaning products for washing up or for cleaning various surfaces, whether they be intended for domestic or industrial use.
In these applications, they can be used alone, mixed together or mixed with other perfuming ingredients, solvents or additives commonly used in perfumery. The nature and type of these co-ingredients does not warrant a more detailed description here, which in any case would not be exhaustive, the skilled person being able to select them on the basis of his general knowledge and according to the nature of the product to be perfumed and the desired olfactory effect. These perfuming ingredients belong to chemical classes as varied as alcohols, aldehydes, ketones, esters, ethers, acetates, nitrites, terpene hydrocarbons, nitrogenous or sulphurous heterocyclic compounds and essential oils of natural or synthetic origin. Many of these ingredients are in any case listed in reference texts such as the book by S. Arctander, Perfume and Flavor Chemicals, 1969, Montclair, N.J., USA, or its more recent versions, or in other works of a similar nature.
The proportions in which the compounds according to the invention can be incorporated into the various aforementioned products vary within a wide range of values. These values are dependent upon the nature of the article or product to be perfumed and on the desired olfactory effect as well as the nature of the co-ingredients in a given composition when the compounds according to the invention are mixed with perfuming co-ingredients, solvents or additives commonly used in the art.
For example, typical concentrations are in the order of 0.1% to 5% by weight, or even more, of these compounds based on the weight of the composition into which they are incorporated. Concentrations lower than these can be used when these compounds are applied directly in the perfuming of the various consumer products mentioned hereinabove.
The invention will now be described in further detail in the following examples, in which the temperatures are given in degrees Celsius and the abbreviations have the usual meaning in the art.